Self-locking nail



. Sept 5, 1950 A. G. KoLEssAR 2,521,378

SELF-LOCKING NAIL Filed Das. a.y 194e T1 .1- 20 f5 /f /J /y TTORNEY from which the nail is formed;

Patented 5, 1950 assura orifice senr-Looms Nan.

Andrew G. Kolessar, Linden, N. J., assignor to Elastic Stop- Nut Corporation of America, Union,-N. J., a corporation oi Delaware Appiimicn December s, 194s, semi No. ,m

2 claim. (ci. as-u) The present invention relates to self-locking nails and has particular reference to sheet metal nails of the kind having two associated shanks or legs of unequal length joined together at the head end of the nail by a collapsible head portion, the collapsing of which when the nail is driven producing relative longitudinal movement between the legs which in turn causes a spreading distortion of the nail to lock it in soft material of nbrous or like nature in which ordinary nails do not have suicient holding power. Still more.specically the invention is in the nature of an improvement in the form of nail configuration, and adjacent to this laperture notches Il and I3 are provided at opposite sides of the strip. Adjacent to the end of the strip opposite the pointed end I2 an aperture 23 is provided which in the embodiment illustrated is of chevron form. This aperture may be of different form but should be so shaped as to provide a projection 22, advantageously but not necessarily pointed, pointing away from the addisclosed in the applications of Robert L. Hallock,

Serial No. 568,2791/2 and Serial No. 578,153, filed December 15,1944, and February 16, 1945, respectively.

For reasons which will hereinafter be more fully pointed out, nails of the above described general type as heretofore developed, while operating very satisfactorily for their intended purpose, have been found in practice to require a certain amount of care and acquired skill on the part of the user in driving the nail, and the general object of the present invention is to provide an improved nail, the construction of which, particularly in the head end of the nail, is such that itlmay readily and surely be driven without the exercise of any more care or skill than is required to drive an ordinary nail. Other and more detailed objects will appear as this speciilcation proceeds and for a better understanding of the invention and the manner in which the desired objects are achieved, reference may best be had to the following description of a preferred embodiment of the invention taken in conjunction with the accompanying drawings forming a part hereof, inwhich:

Fig. 1 is a plan view of a sheet metal bla Fig. 2 is an elevation of the formed nail;

- l Fig. 3 is a section taken on the line III-III of Fig. 2;

Fig. 4 is a section taken on the line IV`IV of Fig. 3; and 'Y A v Fig. 5 is a section similar to Fig. 3 showing the nail after being driven to secure two bodies of material together.

Referring now more particularly to Fig. l the blank I0 consists of a relatively long and narrow strip of sheet metal, usually sheet steel, having parallel sides and a point `I2 at one end. In thecentral region of the stripv there is provided an aperture I4 which in the embodiment illustrated is D-shaped but which may be of other jacent end of thev blank. Further, and between the aperture and the adjacent end of the blank, an additional aperture 24 is advantageously provided. In the embodiment illustrated this latter aperture is in the form of a circular hole but may be of other conguration.' Near its pointed endthe blank is sheared to provide a small projection or lip 26 pointing toward the adjacent end of the blank.

By suitable bending and forming operations of known character the blank is shaped to the form shown in Figs. 2 and 3. By these operations the blank is bent along the bend lines 2l. 30 and 32 to form a leg or shank portion 34. a head portion 36 formed by the material bee tween the bend lines 23 and 32 and a second leg or shank portion 33.

As will be seen from the drawings the' shank 34 is longer than the shank 33 and as seen from Figs. 2 and 3 the shank 34 extends beyond the shorter shank 38 at both ends of the nail. At the head end of the nail the shanks are connected by the head 36 which is of loop-like conguration extending laterally of the nail.

Advantageously the head is of v-form comprising a flat plate-like abutment portion 33a joined to the shank 38 and a similar plate-like portion 36h joined to the shank 34. These portions of the head are joined by an acute bend stantially sheathing the shorter or holding shank in which is located the aperture I4 which is operative to weaken the structure at this point and render the head more readily collapsible.

As will be seen from the drawings the shanks 34 and 33 are bent to channel form. In the example illustrated the channel is of generally U- shaped configuration but it may be V-shaped i or of other suitable configurationproviding a channel. The channel section is of primary iln- 'VI' portance with respectrto the longer shank 34, thisshank being the driving shank of the nail. and the channelsectionailording longitudinal In order to provide a suitable rigid driving point for penetrating material, the portion ot shank 34 extending beyond the end of the shank 3B is preferably crimped at 34a to form a narrower channel than the main portion of the shank. Also as seen in Fig. 3 the base of the channel portion 34a is slightly off-set laterally with respect to the base portion of the main part of the shank 34, so that the portion 34a substantially masks the free end of the shorter shank 38 and as will be seen from Figs. 2 and 3 the portion 34a of the longer shank is of substantially the same cross sectional dimensions as the shorter shank 38.

When the blank is bent and formed to produce the finished nail, the projection 22, which after the bending operation points toward the head end of the nail, is bent outwardlyv slightly away from the channel side of the shank 38, and the projection or lip 26, which points toward the penetrating end of the nail, is bent slightly inwardly toward the channel side of the shank.

The two projections as will be seen from Figs. 2 and 3 engage and preferably as shown overlap angularly so that they are in obliquely connected or interlocking relation. While such overlap of the two projections is not essential, it is advantageous since it operates as a retaining means for holding the lower end of the shank 38 in closely adjacent relation to the shank 34.

The structure thus far described is in accord'r ance with the disclosures in the previously mentioned Hallock applications, and in Fig. 5 the action of the nail when driven is illustrated. In this figure the nail is shown driven home in rela.- tively soft material, being illustrated by way of example as driven into a wallboard of fibrous material or the like to hold a shingle or other body 42, which if of very hard or dense material may be provided with a, pre-formed nail hole in accordance with common practice. When the nail is driven home the head is collapsed due to the abutting contact of the head portion 36a with the surface of the work, this collapsing action acting to pull the short or holding shank longitudinally toward the head of the nail relative to the longer or driving shank 34. The aperture 20 in the shorter shank, a substantial portion of which lies above the projection 22, provides a weakened portion in this shank and the interengagement of the projections 22 and 26 provides a fulcrum which upon relative movement between the Shanks causes the lower portion of the shorter shank to be bent outwardly as shown in Fig. 5 to lock the nail in the material into which it is driven. The small aperture 24 provides a further weakened place in the portion of the shank 38 which bends outwardly so that in case the nail is driven into material so dense or hard as to make difficult the bending of the holding portion of the shank to the right angle position shown in Fig. 5, this portion of the shank itself can distort or bend so as not to penetrate laterally so far into the material. Obviously the denser the material the less is the lateral distortion required in order to secure adequate holding power.

Nails of the above described kind, as heretofore made and used, have been formed with the driving leg 34 perfectly straight from end to end, except for the offset portion 34a at the pointed end of the nail. Experience in the manufacture of the nails has demonstrated that when the sheet metal blank is bent to form the nail the bend along the bending line 32 must be made with a substantial radius as indicated at 34h. l't has been found that if this is not done the metal will ilO in many instances crack at `,the time it is bent and even if it does not crack at that time may crack when the sharply bent portion is struck by a hammer when the nail is driven.

From observation of Fig. 3 it will be apparent that the bend at the top of the nail results in the highest portion of the nail, which is apt to be struck first by a hammer head, being in the form of an edge or line 34e. It will further be evident from Fig. 3 that if the driving shank 34 is straight, the line 34e, which for convenience may be referred to as the striking line, will be laterally offset to the left as viewed in the figure from a plane passing through the pointed end l2 of the nail and extending longitudinally of the nail. The magnitude of such offset is not large but in practice it has been found suflicient so that in many instances when nails were driven by artisans accustomed to driving fiat headed nails. the offset was suilicient to cause the head end of the nail to be deiiected laterally when struck, in much the same manner as if the nail had been struck by a glancing blow of the hammer rather than a correct blow. This tendency of the nail as previously formed to fail to drive properly when struck in the ordinary manner could be overcome by the user by striking the nail in such manner that the hammer head did not descend on the nail head in line with the axis of the nail, but that procedure involved the acquisition of a special skill in driving the nail.

The deficiency as above described has been eliminated by the present invention through the bending of the upper portion 34d of the driving leg 34 laterally to the side of the nail opposite the side on which the head of the nail extends, preferably by an amount such that the striking line 34C at the top of the head is longitudinally in line with the point of the nail.

One of the requisites of a satisfactory nail of the kind under consideration is that the driving leg shall have sufficient longitudinal rigidity so that the nail can be driven into desired materials, some of which may be relatively dense, as for example when the nail may be required to be driven through relatively soft material such as the material 40 at a place where that material may be backed up by a wooden stud or the like into which the point of the nail may have to penetrate before the nail is driven home. It has been found from actual experience that the amount of bending of the upper portion 34d of the driving leg required to effect the purpose of the present invention is not sufficient to impair the rigidity of the driving leg. In other words, when the nail is driven into'material as hard as wood, there is no tendency for the head of the nail to collapse until it is collapsed in the intended manner by contact of the abutment portion 36a of thehead with the surface of the work.

Fig. 3 illustrates a preferred proportioning of the parts which have been found from actual experience to provide highly satisfactory operation. As will be seen from this figure the portions 36a and 36h of the head and the bent portion 34d of the driving leg which extends beyond the holding leg form a substantially isosceles triangle of which the base is formed by the portion 34d, the relation of the parts and the extent to which the portion 34d` is bent relative to the axis of the nail resulting in the median line of the triangle lying at an acute angle with respect to a plane normal to the axis of the nail. Advantageously, as shown, the triangle is further substantially equilateral.

Also as will be observed from Figs. 3 and 5, the

lengths of the portions 36a and 36h of the head are substantially equal so that when the head is collapsed by driving the nail h me the bending of the abutment portion 36a to a position substantially at right angles to the longitudinal axis of the nail tends to pull the portion 36h laterally to the left as viewed in Fig. 3, the portion 36h acting in effect as a tension member tending to straighten the bent portion 34d of the driving leg into alignment with the remaining portion of this leg. Thus in spite of the bend in the driving leg the nail head will in practice not collapse until the nail is driven home and the nail will furthermore tend to straighten out as it is driven home rather than tend to bend or distort in another and undesired manner.v

While for purposes of illustration a preferred example of nail has been disclosed, it Willbe apparent that the invention is not limited in its scope to nails of the specic form shown but is also applicable to other nails of the kind under consideration, which may among other things achieve their locking action by means other than the locking means herein shown. The invention is accordingly to be understood as covering al1 forms of nail construction falling within the Vscope of the appended claims.

I claim:

1. A self-locking nail comprising an integral sheet metal body formed to provide a driving leg and a contiguous holding leg joined by a, collapsible head of loop-like form, said driving leg extending beyond said holding leg and having a sharp penetrating end, said collapsible head being of generally V-shape formed by upper and lower portions extending generally laterally of the nail at an acute angle with respect to each other, the lower portion joining the head end of the holding leg and the upper portion joining the head end of the driving leg, said driving leg being of channel form the web and flanges of which extend to 'l and join said upper portion to prevent collapsing of said head end, the head end of the driving leg being bent obliquely with respect to the axis of said driving leg to join the upper portion of the head at the side of the nail opposite to the side on which the apex of said head is located, said point of juncture being in substantial alignment with the axis of the point of the nail to prevent deflection thereof when struck a driving blow, said holding leg being disposed within the channel of said driving leg, and interengaging means between said legs to cause deflection of said holding leg upon collapsing of said head.

2. A self-locking nail comprising an integral sheet metal body formed to provide a driving leg and a contiguous holding leg joined by a collapsible head of loop-like form, said driving leg and holding leg being of channel form, said driving leg substantially sheathing the holding leg and having a sharp penetrating end of smaller channel form extending beyond and masking one end 'of said holding leg, said collapsible head being upper portion of the head at the side of the nail opposite to the side on which the apex of said head is located, said point of juncture being in substantial alignment with the axis of the penetrating end of said nail to prevent deflection thereof when struck a driving blow, and interengaging means between said legs to cause deflection of said holding leg upon collapsing of said head.

ANDREW G. KOLESSAR.

REFERENCES CITED i The following references are of record in the file of this patent:

UNITED STATES PATENTS 

